As known in the industry, dental implants can be stored prior to their use in a sealed container, which is preferably filled with a storage fluid, as disclosed in U.S. Pat. No. 6,261,097B1, which is commonly assigned with the assignee of the present application and the entire disclosure of which is incorporated herein for all purposes.
During storage, a dental implant is temporarily coupled to a holding device, which firmly retains the dental implant in position within an ampule within the container. When the dental implant is removed from the ampule for implantation into a jawbone, the holding device can be gripped by a user for positioning at an implant site. Furthermore, the holding device is adapted to enable a temporary yet positive engagement with a manipulating tool, which facilitates the removal of the dental implant from the ampule and the placement thereof into the bone at the implant site. Ultimately, when the dental implant is implanted at the desired site in the bone, the holding device can be removed from the dental implant. Nevertheless, as the holding device is screwed to the dental implant, the overall handling is tedious.
International Publication No. WO-A1-2005/037126, which is also commonly assigned and the entire disclosure of which is incorporated herein for all purposes, discloses a holding device wherein the use of a screw for coupling the holding device to the dental implant is avoided.
As shown in FIGS. 1-3, the holding device, which is generally designated by reference numeral 1, includes an engagement section 2 adapted for positive engagement with a manipulating tool (not shown). The engagement section 2 is embodied as a polygonally shaped end, for instance, an octagonally shaped end. As shown in FIG. 2, a circumferential groove 3 is provided adjacent the engagement section 2 for accommodating an O-ring 3A, which has a securing function to the manipulating tool.
Furthermore, as shown in FIGS. 1 and 1A, the holding device 1 includes a retention section 4 having two annular shoulders 5 and 7 adjoined by an intermediate cylindrical section 6 having a reduced diameter. The retention section 4 is adapted to engage an inner ampule 20. The retention section 4 is joined to the engagement section 2 by a breaking point 30.
The holding device 1 further includes a clamping section 8 adjacent to the retention section 4. The clamping section 8 includes a first circumferential groove 9, a force transmission element 10 having an octagonal shape for positive engagement with a dental implant 14, a second circumferential groove 11 and a tapered member 12. As shown in FIG. 3, the second circumferential groove 11 is provided with a clamping or locking ring 13 made of PEEK (poly ether ether ketone), which includes a peripheral clearance 13A for facilitating the mounting thereof.
As shown in FIG. 2, the dental implant 14 includes a cavity 15 having an inner surface 17 that matches the outer surface of the force transmission element 10, such that a positive engagement between the dental implant 14 and the holding device 1 can be provided to allow the dental implant 14 to be rotationally secured to the holding device 1. As shown in FIG. 2A, the cavity 15 of the dental implant 14 further includes an undercut 18 dimensioned to clampingly receive the lock ring 13, and a conical terminal section 19 enclosing the first circumferential groove 9 of the clamping section 8 of the holding device 1.
Certain disadvantages have been identified from the known holding devices. For example, the clamping force of the PEEK locking ring 13 changes with time or is variable ab initio. Thus, it is difficult to precisely adjust the clamping force when the implantation is carried out. This problem is pronounced, if the dental implant is stored over a long time span, and is even further aggravated if the storage medium is a fluid. Furthermore, the prior art locking ring tends to release carbon, which may damage the surface of the dental implant, particularly dental implant surfaces treated in order to improve bone cell attachment, for example sandblasted and/or acid etched and/or coated surfaces. In addition, the manufacturing tolerances of the PEEK locking ring are very strict, and therefore the production thereof may become difficult.
U.S. Pat. No. 8,070,491, which is also commonly assigned and the entire disclosure of which is incorporated herein for all purposes, discloses a holding device which includes a separately formed clamping member 113 made of a plastic material or a clamping member 223 in the shape of an arm milled from a lateral wall of a force transmission element 210. Both clamping members 113 and 223 extend in their non-compressed state beyond the perimeter of the force transmission element. This enables the members to snap into an implant undercut 18 directly distally adjacent to the area of the inner implant surface 17 that matches the force transmission element 110, 210 of the holding device. For the holding device having a separately formed clamping member, additional steps of manufacturing and attaching the clamping member are required, which compromises the integrity and operability of the holding device and also increases the cost of manufacture. Furthermore, it has been found that the separate plastic component shrinks over time and thus, loses its ability to securely grip the dental implant. In addition, in order to connect the separately formed clamping member to the holding member, the force transmission element must be at least partially hollow, thus reducing the strength of this element. This same problem occurs when the clamping member is milled from the lateral wall of the force transmission element, namely the strength of the force transmission element is reduced due to the milled lateral wall thereof. Furthermore, the arm-shaped clamping member, milled from the lateral wall of the force transmission element, may suffer from distortion during the rotation of the force transmission element, which can lead to disconnection of the milled arm(s) from the dental implant. In addition, the process of milling an arm from the lateral wall of the force transmission element requires additional steps.
Therefore, it is desirable to provide an improved holding device, which overcomes one or more of the disadvantages of the known holding devices.